The Western States Roofing Contractors Association (WSRCA), thermoplastic polyolefin (TPO) roofing manufacturers, and the National Research Council Canada started a TPO Weathering Farm Project in 2000 to examine weathering characteristics of TPO roof membranes by exposing them to various weather conditions of four distinctly different climatic regions in the Western United States. The goal was to provide technical and performance information to the Western States Roofing Contractors Association membership, and the North American roofing community at large, regarding TPO roof membranes' attributes, performance properties, and resistance to weathering. The results are applicable to other regions in North America as the roofs are in four disti...